CONICET | Buscador de Institutos y Recursos Humanos

The penicillin-resistant Spain9V-3 clone of Streptococcus pneumoniae is widespread and presents different serotype variants originated by recombination of the capsular genes. In this work, the genetic relatedness of 29 invasive pneumococci isolated from the central region of Argentina (Cordoba, Buenos Aires, Santa Fe and La Pampa provinces), was assessed by MLST. All the penicillin-non-susceptible isolates studied (21/29) belonged to a serotype 14 variant of the Spain9V-3 clone. This clone was predominant, suggesting that it was responsible of the penicillin-resistance spread in our region. Interestingly, our serotype 14 variant (named Cordoba S14V) was differentiated from the European one by the pbp1a gene, suggesting a different recombinational replacement of the capsular genes. The putative recombinational sites were analyzed, resulting in the proximal crossover point being clearly localized in the spr0309 gene, with the distal site being restricted to the recU gene, confirming a different recombinational event. The analysis of the dexB, cpsB, aliA and pbp1a genes from our strains showed a high homology with the corresponding genes of the Spain14-5 clone, suggesting that the capsular genes were provided by this international clone. The analysis of the genetic polymorphisms of the pbp1a (1473-1922 region) and spr0309 (1-790 region) genes is proposed as an epidemiological tool to help recognize the Cordoba S14V of the Spain9V-3 clone. On the other hand, a PCR-BOX and MLST analysis of serotype 14 strains revealed a divergent epidemiology of the Cordoba S14V, suggesting a non-recent dissemination in our paediatric population. We consider that this molecular epidemiology work will be a reference for monitoring the evolution of the serotype 14 variants of Spain9V-3, the emergence of new clones and the impact of pneumococcal vaccination programs in Argentina.